The GOF mutations in the PIK3CD gene and LOF mutations in the PIK3R1 gene result in the hyperactivation of the PI3K/AKT/mammalian target of rapamycin (mTOR) signaling pathway in immune cells, leading to a complex deficiency of cellular and humoral immunity in APDS patients.5 This evidence concerns the gene PIK3CD and activated PI3K-delta syndrome.